AWS S3 cp creates undefined files

Question

While using the aws cli cp command to copy the files recursively, there is a bug which creates some undefined files.

aws s3 cp --recursive $HOME/$MYHOST-$MY         


        

Answer 1

You have configured S3 access logging to write logs into this bucket. Presumably, these are the log files for this bucket.

Why the filenames begin with "undefined" is not clear -- something may have gone wrong when you set up logging for the bucket so that the log file prefix did not get saved -- but the filenames look like the names of the log files that S3 creates.

https://docs.aws.amazon.com/AmazonS3/latest/dev/ServerLogs.html

Best practice is to set up a separate bucket for collecting S3 access logs in each region.